title: The inhibitory effect of proanthocyanidin on soluble and collagen-bound proteases.
abstract: OBJECTIVE
  This study evaluated the inhibitory effect of proanthocyanidin (PA), a natural collagen cross-linker, on soluble and matrix-bound proteases, which are responsible for progressive degradation of exposed collagen fibrils within the hybrid layer and resin-dentine bond failure over time.
  
  
  METHODS
  The inhibitory effects of PA (1%, 2%, 3%, 4.5% and 6%) on soluble recombinant matrix metalloproteinases (MMP-2, -8 and -9) and cysteine cathepsins (cathepsin B and K) were evaluated using MMP and cysteine cathepsins fluorometric assay kits. Chlorhexidine (CHX) was used as an inhibitor control. The effect of PA on endogenous matrix-bound proteases was examined by determining the change in dry mass of demineralized dentine beams and solubilized collagen peptides over 30 days. Two-way ANOVA and Tukey multiple comparison tests were used to analyze the effect of PA and proteases on the percentage inhibition of soluble proteases (α=0.05). Kruskal-Wallis one-way ANOVA and Dunn's multiple comparison tests were used to analyse the effect of PA on loss of dry mass and hydroxyproline content over time (α=0.05).
  
  
  RESULTS
  Proanthocyanidin inactivated more than 90% of soluble recombinant MMP-2, -8 and -9 and around 75-90% of cysteine cathepsin B and K, which was significantly higher than CHX (P<0.05). The inhibition of endogenous proteases by PA increased in a dose-dependent manner. The loss of dry mass and hydroxyproline release in the medium over time was the lowest in dentine beams pretreated with PA<CHX<control (P<0.05).
  
  
  CONCLUSIONS
  Proanthocyanidin exhibited both dentine MMP and cysteine cathepsins inhibition, which was higher than chlorhexidine.
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, China.
authors.forename: Don Jeevanie
authors.initials: DJ
authors.lastname: Epasinghe
authors.forename: Cynthia Kar Yung
authors.initials: CK
authors.lastname: Yiu
authors.forename: Michael Francis
authors.initials: MF
authors.lastname: Burrow
authors.forename: Noriko
authors.initials: N
authors.lastname: Hiraishi
authors.forename: Franklin Russell
authors.initials: FR
authors.lastname: Tay
mesh_terms: D000293:Adolescent; D002401:Cathepsin B / Q000037:antagonists & inhibitors; D056657:Cathepsin K / Q000037:antagonists & inhibitors; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D002710:Chlorhexidine / Q000494:pharmacology; D003094:Collagen / Q000032:analysis / Q000187:drug effects*; D024042:Collagen Type I / Q000032:analysis / Q000187:drug effects; D003804:Dentin / Q000737:chemistry / Q000187:drug effects* / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes; D006801:Humans; D006909:Hydroxyproline / Q000032:analysis / Q000187:drug effects; D020778:Matrix Metalloproteinase 2 / Q000187:drug effects; D020784:Matrix Metalloproteinase 8 / Q000187:drug effects; D020780:Matrix Metalloproteinase 9 / Q000187:drug effects; D061965:Matrix Metalloproteinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010756:Phosphoric Acids / Q000494:pharmacology; D044945:Proanthocyanidins / Q000008:administration & dosage / Q000494:pharmacology*; D012995:Solubility; D013997:Time Factors; D055815:Young Adult
chemical_list: D024042:Collagen Type I; D005456:Fluorescent Dyes; D061965:Matrix Metalloproteinase Inhibitors; D010756:Phosphoric Acids; D044945:Proanthocyanidins; C013221:proanthocyanidin; D003094:Collagen; C030242:phosphoric acid; D002403:Cathepsins; C533912:CTSB protein, human; D002401:Cathepsin B; C534130:CTSK protein, human; D056657:Cathepsin K; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C488762:MMP8 protein, human; D020784:Matrix Metalloproteinase 8; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; D002710:Chlorhexidine; D006909:Hydroxyproline
keywords: Collagen cross-linking; Cystein cathepsins; Dentine; Matrix metalloproteinases; Proanthocyanidin